1. Field of the Invention
The present invention relates generally to an automatic tool changer which is designed to permit the automatic changing of different tools for the spindle of a machining apparatus.
2. Description of the Prior Art
FIG. 6 shows a representative example of attaching a tool to the spindle of a machining apparatus. Specifically, workspindle 1 has a conical hollow chamber 71 whereas cutting tool assembly E has a conical projection 72. Conical projection 72 has a grooved end 73. It is inserted in conical hollow chamber 71 of workspindle 1, and its grooved end 73 is pulled and caught by a collet ( not shown ). Cutting tool 74 can be brought to a desired radial position by driving an adjusting screw 75.
FIG. 7 shows a conventional automatic tool changer to be used with a machining apparatus whose spindle is designed to have a tool attached thereto as shown in FIG. 6. Specifically, the automatic tool changer includes a tool retainer-and-feeder 82, which comprises a tool retainer 85 in the form of a conveyor having a plurality of holes 81 to hold different tools E. Tool retainer-and-feeder 82 is placed adjacent to the spindle 1 of a machining apparatus, which spindle 1 is adapted to be raised or lowered as indicated by the double headed arrow. A transporting arm ( not shown ) is provided to transport tools from spindle 1 to tool retainer-and-feeder 82 and vice versa. In attaching tool E to spindle 1 of the machining apparatus the transporting arm is used to: grip and pull up tool E; carry tool E towards spindle 1; turn and put tool E into a horizontal position; and insert its conical end 72 into cylindrical hollow chamber 71 of spindle 1. Tool E is fixed to spindle 1 by an associated collet ( not shown ), and spindle 1 is lowered to put tool E in the correct position relative to a given work. In attaching another tool to spindle 1 in place of the used one the transporting arm works in the reversed way, thus carrying and putting tool E in a selected hole 81 in the conveyor 85. Then, the transporting arm picks up another tool to attach it to spindle 1 in the same way as described earlier.
As seen from FIG. 7, every tool is put in a selected hole 81 with its cylindrical end 72 inserted in the hole, and with its flange 86 engages caught by the circumference of the hole.
As described above, the changing of tools requires a series of actions, that is, tool's rising, traversing, turning to the horizontal position and fitting-in. Disadvantageously, this makes the tool changing mechanism complicated and bulky.
The transporting arm must follow one and the same path both in removing a used tool from the spindle and in attaching a new tool to the spindle. This prevents the sequential actions for attaching a new tool to the spindle of a machining apparatus from starting before having completed the sequential actions for removing the used tool from the spindle of the machining apparatus. Disadvantageously, this requires an extended time involved for changing tools.